The present invention relates to residential heating systems and other indoor comfort systems, and is more particularly concerned with improvements to baseboard radiator heating systems. The invention is more specifically concerned with an improved baseboard radiator of the tube and fin type.
Baseboard room heating systems are commonly employed in homes and commercial spaces because of their simplicity of construction and operation. In a typical hot water heated system, water circulates from a furnace or boiler through a zone loop which may have one or more baseboard radiators. The flow is in series through the radiators and then the water is returned to the furnace or boiler. Baseboard hot water heating is perhaps the simplest method of heating that can be installed in a comfort space.
In the typical baseboard heater or radiator (sometimes called a convector) that is in common use, there is a copper tube or pipe, through which the hot water flows, and a series of fins or vanes, usually made of aluminum, which are in good thermal contact with the copper tube. The tube penetrates through aligned apertures in the fins or vanes. The heat flows to the vanes, and the vanes heat the room air that contacts them. The heated air moves by convection upwards into the room or comfort space. There is typically a baseboard cover positioned over the radiator or convector, with a damper to control air flow past the radiator.
Copper tubing is universally used as the hot water conduit through the radiator or convector. Copper is favored for a number of reasons, including good heat conduction to bring the heat to the fins or vanes, and because the copper material can be easily soldered or brazed to other tubing in the loop.
The use of copper tubing does have some disadvantages, however. One disadvantage is the expense involved, as copper is typically about three times as costly, pound for pound, as aluminum. Also, copper is relatively heavy, approximately three times the weight density of aluminum. If aluminum were used as the water conduit, then tubing the same size would have only one ninth the cost of copper tubing. Stated otherwise, for the same or lower cost, aluminum tubing of greater diameter can be used in substitution for copper tubing, without loss of thermal characteristics, and with other advantages, such as reduced velocity noise, elimination of thermal expansion noise, and reduced drop of pressure head in the loop.
Velocity noise is encountered in a baseboard radiator when the flow of water through the tubing is too great for the diameter of the tube, i.e., too small a tube diameter for the number of gallons per minute of flow needed. Typically, this problem would be addressed by increasing the size of the baseboard radiator, which increases the cost significantly, or by increasing the water temperature, which permits the user to have a lower flow rate, but also results in higher heating costs.
Thermal expansion noise commonly occurs with conventional copper/aluminum baseboard radiators, due to the difference in thermal expansion coefficient as between the copper tube and the aluminum vanes. This produces an annoying clicking or ticking noise, especially at the onset of a heating cycle when the radiator is heating up.
In view of the problems encountered with copper/aluminum baseboard heat radiators, it would seem that aluminum tubing would be an ideal substitute for the copper tubing in the baseboard radiator. However, there are issues that make aluminum tubing or aluminum pipe difficult to use in a hot water system.
Aluminum is difficult and expensive to weld to aluminum itself or to other metals, and cannot simply be soldered or brazed to copper, steel, or brass; so the connectivity of the aluminum/aluminum baseboard radiator to the rest of the system is a difficult hurdle to surmount. Also, to date no one has proposed an effective way to install aluminum vanes or fins onto an aluminum pipe or tube for a baseboard heat radiator.
Thus, the object of this invention is to find a way to overcome these difficulties, so that the advantages of an aluminum/aluminum baseboard heater or radiator can be enjoyed, namely, lower cost installation, reduced velocity noise, and avoidance of thermal expansion ticking noises, but without any loss of durability, ruggedness, or thermal efficiency. A related object is to find a way to terminate aluminum pipe or tubing so it can be connected into the flow loop.